Molecular Assembly Of Photosynthetic Components In Plants And Their Photoelectric Properties

Photosynthesis is considered as the most important reaction on earth.After billions of years of evolution and development,photosynthesis has formed an effective mechanism of solar energy fixation and conversion.However,the actual light energy utilization rate of plants is very low.In addition,the photosynthetic efficiency of crops in agricultural production is greatly affected by light conditions.Research using plant photosynthetic components as building blocks towards photoactive electrode through a co-assembly approach for simulation and regulation of photosynthesis in vitro,is considered to be one of the most potential solutions for the issue of solar energy utilization in all fields.The unique property of photosystem II?PSII?to split water in ambient condition makes it the heart of this process,which has attracted more and more attention.The current thesis employed PSII and thylakoid membrane?TM?as building blocks and constructed various photoactive composite films utilizing molecular assembly strategy.The assembly behavior and photoelectric properties of the films were characterized.The influences of certain chemical and environmental factors on photo-induced electron transfer of PSII were investigated.The sprayed layer-by-layer technique was developed due to its high potential in the assembly of photoactive components.First,water soluble CdTe quantum dots with fluorescence-emission peak at 680 nm were synthesized.With layer-by-layer technique,polyallylamine and CdTe quantum dots were co-assembled on indium tin oxide?ITO?substrates and the achieved multilayerd films exhibited red fluorescence and pored structure.PSII was further absorbed to above films and the obtained composite films PSII-PAH/CdTe with lower content of PSII generated 10-20%higher photocurrent density compared to pure PSII films under UV light?365 nm?irradiation.This might be attributed to radiation energy transfer occurred between CdTe and PSII,thus gave rise to the enhanced photocurrent density.Second,TM and graphene oxide were used as building blocks for the construction of photoanode utilizing one step co-assembly process and photocurrents of mediated electron transfer?MET?of composite films were investigated.The functional groups present in graphene oxide were able to increase the local concentration of the electrochemical mediator thus enhance the MET photocurrent density.The highest MET photocurrent density occured when graphene oxide:Chl?m/m?is 2:1,which was 2.5 times higher than pure TM films.Control experiments confirmed that the electron transfer pathway in our system is PSII ? plastoquinone ?[Fe?CN?₆]^3-/4-? ITO electrode.Finally,a homebuilt spraying device for LbL was set up,and polyelectrolyte multilayered film of PAH/PSS were successfully assembled using LbL technique.The film growth behavior of the multilayered film under different assemble parameters was studied.By changing the number of layers,the concentration of polyelectrolyte,the ion strength in solution and the spraying time,the thickness of multilayered film can be precisely regulated at nanoscale.